What type of chip is characterized by forming a long, curled string?

The type of chip characterized by forming a long, curled string is known as continuous chips. This type of chip formation occurs during processes with consistent cutting conditions, such as in machining operations with a stable feed rate, low cutting speed, and sharp cutting tools. Continuous chips are typically formed in ductile materials where the metal is sheared continuously rather than breaking apart.

The long, curled shape of continuous chips is a result of the plastic deformation of the material during cutting, allowing the chip to flow out smoothly rather than fracturing. This can be beneficial as it often indicates a more efficient cutting process, producing smoother surfaces on the workpiece and requiring less force.

In contrast, discontinuous chips would break into smaller pieces and may not produce a long curled shape; they are often found during machining of brittle materials. Broken chips would be even more fragmented, while thin chips are characterized more by their thickness rather than their formation shape.